Chemo-mechanical expansion delivery system

Abstract

System for delivery of a biologically active substance into an environment. The container is comprised of a single member or two mated members and defines first and second compartments. The container includes pores in at least a portion of the container defining the first compartment. The first compartment contains a polymer gel network which undergoes a volume expansion in response to an environmental condition which varies in the biological environment. The second compartment contains an effective amount of a biologically active compound and may include at least one passageway communicating with the biological environment. Drug delivery is initiated and continues only when the appropriate environmental condition or trigger is met, whereupon volume expansion of the polymer gel network causes the biologically active compound to be discharged into the biological environment.

What is claimed is: 
     
       1. Apparatus for controlled delivery of a biologically active compound to a biological environment comprising: a container comprised of a single member or two mated members, the container defining first and second compartments and comprising pores in at least a portion of the container defining the first compartment,   the first compartment containing a polymer gel network which undergoes a volume expansion in response to an environmental condition which varies in the biological environment,   the second compartment containing an effective amount of a biologically active compound and including at least one passageway communicating with the biological environment,   whereupon volume expansion of the polymer gel network causes the biologically active compound to be discharged into the biological environment through the passageway.   
     
     
       2. Apparatus for controlled delivery of a biologically active compound to a biological environment comprising: a container comprising pores in at least a portion of the container;   a first compartment within the container containing a polymer gel network which undergoes a volume expansion in response to an environmental condition which varies in the biological environment;   a second compartment containing an effective amount of a biologically active compound and including at least one passageway communicating with the biological environment, the second compartment disposed within the first compartment;   whereupon volume expansion of the polymer gel network causes the biologically active compound to be discharged into the biological environment through the passageway.   
     
     
       3. Apparatus for controlled delivery of a biologically active compound to a biological environment comprising: a container comprising pores in at least a portion of the container;   a first compartment within the container containing a polymer gel network which undergoes a volume expansion in response to an environmental condition which varies in the biological environment;   a second compartment containing an effective amount of a biologically active compound in communication with the biological environment through the pores, the first compartment disposed within the second compartment;   whereupon volume expansion of the polymer gel network causes the biologically active compound to be discharged through the pores of the container into the biological environment through the passageway.   
     
     
       4. Apparatus for controlled delivery of a biologically active compound to a biological environment comprising: a container comprised of a single member or two mated and comprising pores in at least a portion of the container, the container defining a space housing:   upper and lower compartments containing a polymer gel network which undergoes a volume expansion in response to an environmental condition which varies in the biological environment, the upper and lower compartment in communication with the biological environment through the container pores; and   an inner compartment containing an effective amount of a biologically active compound and including at least one passageway communicating with the biological environment,   whereupon volume expansion of the polymer gel network causes the biologically active compound to be discharged into the biological environment through the passageway.   
     
     
       5. The apparatus of claim 1, further comprising a biocompatible membrane substantially surrounding the container. 
     
     
       6. The apparatus of claim 1, wherein the environmental condition is pH. 
     
     
       7. The apparatus of claim 1, wherein the polymer gel network is in an expanded state at low pH and in an expanded state had a high pH. 
     
     
       8. The apparatus of claim 1, wherein the apparatus further comprises a partition positioned between the first and second compartments. 
     
     
       9. The apparatus of claim 1, wherein the crosslinked polymer gel network comprises a polymer selected from the group consisting of interpenetrating polymer networks, hydroxypropylcellulose, hydropropylmethylcellulose, starch, and hydroxyethylcellulose. 
     
     
       10. The apparatus of claim 1 wherein the environmental condition is selected from the group consisting of temperature, solvent composition, pH, electric field, magnetic field, light intensity, light wavelength, pressure, ionic strength, osmolarity, electric current, redox potential and presence of specific enzymes. 
     
     
       11. The apparatus of claim 1 wherein the gel network exhibits a continuous volume change. 
     
     
       12. The apparatus of claim 1 wherein the responsive gel network exhibits a discontinuous volume change. 
     
     
       13. The apparatus of claim 1, wherein the container comprises pores over at least a portion of the container defining the second compartment. 
     
     
       14. The apparatus of claim 1, wherein the pores are non-uniformly distributed in the container. 
     
     
       15. The apparatus of claim 1, wherein the pores are of non-uniform diameter. 
     
     
       16. The apparatus of claim 1, wherein the pores are of uniform diameter. 
     
     
       17. The apparatus of claim 8, wherein the partition is fixed within the container and capable of deforming to accommodate the expanding hydrogel. 
     
     
       18. The apparatus of claim 8, wherein the partition is substantially rigid and capable of displacement to accommodate the expanding hydrogel. 
     
     
       19. The apparatus of claim 8, wherein the partition comprises a superabsorbant hydrogel. 
     
     
       20. Apparatus of claim 1, wherein the compartment is implanted into a body. 
     
     
       21. Apparatus of claim 1, wherein the compartment is external to the body.